The effect of frequency of harvesting grass for silage and level of concentrate supplementation on the intake and performance of beef cattle

Abstract

A randomized-block experiment has been carried out over 2 consecutive years to examine the effects of frequency of harvesting grass for silage, and level of concentrate supplementation, on the intake and performance of beef cattle. Swards of S24 perennial ryegrass were harvested at 6-, 9- and 12-week intervals throughout the growing season, commencing on 14 May, 4 June and 25 June respectively. The three silages were offered ad libitum with 0, 1, 2 or 3 kg per head per day of cereal-based concentrates to 84 Hereford-cross suckled calves (mean initial live weight 313 kg) in a 3 × 4 factorial design experiment in each year. The treatments were imposed for a mean period of 100 days. The digestible organic matter in the dry-matter values of the silages harvested at 6-, 9- and 12-week intervals were 0·684, 0·646 and 0·607 respectively. The mean silage dry-matter intakes and live-weight gains for the silages harvested at 6-, 9- and 12-week intervals were 4·75, 4·70 and 4·74 (s.e. 0·08) kg/day, and 0·75, 0·67 and 0·52 (s.e. 0·020) kg/day, respectively. The mean silage dry-matter intakes and live-weight gains for the supplement at 0, 1, 2 and 3kg/day were 5·23, 4·79, 4·72 and 4·17 (s.e. 009)kg/day, and 0·38, 0·57, 0·75 and 0·88 (s.e. 0·023) kg/day, respectively. There was a significant interaction between cutting interval and level of supplementation for live-weight gain, the response to supplementation declining as silage digestibility increased.